Carbureted LS Crate Engines: Modern Horsepower For Your Classic Ride

Gearheads have been swapping engines for as long as any of us can remember. Shoehorning a different engine with more power under the hood of a classic ride is commonplace, and almost mandatory to receive any street credibility. The introduction of GM’s LS engine made swapping a bigger and better engine into your classic ride a whole different ballgame. That is because an LS engine swap requires more than just sliding it in place and connecting a few wires and a fuel line – or does it? While a lot of guys completing an LS engine swap opt to keep the fuel injection and beef up the fuel fuel delivery system, some others still like the simplicity of a carburetor and a stock fuel system.

Installing a carbureted LS engine does not mean that an EFI-specific fuel system is required. Also the ignition controller is an easily-overcome modern piece of the puzzle. To help those wanting a modern engine with an old school look, we enlisted the help of BluePrint Engines, Edelbrock Performance, Late Model Engines, Pace Performance, and Scoggin-Dickey Parts Center – some of the best crate engine suppliers in the business – to provide us with the information you guys need to help you upgrade your ride with carbureted, LS-crate motivation.

Swapping an LS engine has become common practice, and many of those swaps are in classic cars and still incorporate a carburetor.

When it first tested in January 1995, the new LS differed significantly from the traditional small-block. GM obviously wanted the new LS engine to attain a legendary status, so they chose the already legendary Corvette as the platform for the LS engine’s debut in 1997.

The LS engine brought many new features to the table, like valve cover-mounted coils, eliminating the need for a distributor, hypereutectic-alloy pistons, powdered-metal connecting rods, and six-bolt main caps. This provides a very strong bottom end for the engine right out of the box. Increasing power output no longer requires the addition of an aftermarket main cap stud girdle like was needed in a traditional small or big-block engine. The LS oil pan sees double duty as well, not only holding the life blood of the engine, but it also aids in the block’s structural rigidity with it’s thick, cast aluminum design.

The traditional small-block design featured a cylinder head bolt pattern with a five-bolt pentagonal arrangement, but this was replaced with a four-bolt square pattern, which is very similar to the 1964 through 1990 Oldsmobile V8 engines. Another major change involes the firing order, which was changed from 1-8-4-3-6-5-7-2, to 1-8-7-2-6-5-4-3. Chevrolet did this to improve idle stability and decrease crankshaft haromonics, this allowed the LS to run higher compression ratios without the possibilty of predetonation and localized overheating issues. This also contributed to an exhaust tone, that is much different from the sound we’re all used to from a Chevrolet V8 engine.

When introduced in 1997, no one expected the LS engine to take the engine swap world by storm. Image courtesy of GM.

While originally born into the Corvette, the LS family tree spread quickly to include base model cast-iron LS engines showing up in everything from trucks and SUV’s, to lightweight aluminum versions that are found in pavement shredding performance models like the Camaro, G8, GTO, and Cadillac CTS-V, as well as maintaining the pinacle of performance in the Corvette. The amazing design of the LS engine helps make the aluminum block nearly as stong as an iron block at a fraction of the weight.

The horsepower possibilities of the LS engine are remarkable. It’s not unreasonable to pull an LS engine out of a car or truck, install a few, basic hop up items, and top 500 horses at the flywheel. The virtually unlimited capabilities of the LS engine makes this lightweight, compact power-maker very desirable for swapping into just about anything with wheels. Many vintage cars, street rods, and even racecars have reaped the benefits of outstanding horsepower numbers, durability, and impressive fuel economy to boot. You can even check out another article about a budget LS swap right here.

Making The Grade

Don’t let the small displacement fool you, while only 376 cubic inches, this LS3 puts out a whopping 550hp. – Johnny McDevitt

Deciding what LS engines we needed to list in this “LS Crate Engine Buyer’s Guide” was not an easy task. While it would have been simple to only include fuel injected applications, which many enthusiasts have done, there is one option that draws controversy, and that is adding a carburetor to this modern engine. In the interest of not following the masses, we at Chevy Hardcore decided to go “old school cool” and look at non-conventional LS engines. We wanted show you options for getting the performance and reliability of a new, modern powerplant, while retaining the classic look and function of a carburetor. We wanted the list to include engines that would be very streetable throughout the week while having to endure the 9-to-5 grind, but also be able to shred more than just a little rubber at the track or stoplight.

So here you’ll find several options for your next LS swap. What are you waiting for? Modernize that classic ride.

We reached out to Johnny McDevitt/Director Of Vendor Relations at Pace Performance, and he gave us the low down on their LS3 crate engine offering. Don’t let the small displacement size fool you, while only 376 cubic-inches, this LS3 puts out a whopping 550 horsepower. You’ll surprise many an import with this power producer under the hood.

The Pace Performance 6.2-liter LS3 starts with the Chevrolet Performance 525 horsepower LS crate engine, and Pace adds a front distributor drive timing cover kit and an HEI distributor, making this a turnkey crate engine. Nothing else is needed, no Engine Control Unit (ECU) or wiring harness. The timing cover and custom water pump has heater hose ports and standard radiator hose locations. This power package starts with a cast aluminum block with a 4.065-inch bore and 3.622 inches of stroke. Swinging on a nodular-iron crankshaft is a set of hypereutectic pistons on powdered-metal rods. Keeping everything balanced is an ATI balancer.

The cylinder heads are aluminum with L92-style ports, 68cc combustion chambers, and 2.165/1.590-inch valves. The cast rocker arms are a 1.7:1 ratio, and a set of Chevrolet valve covers top it off. With a compression ratio of 10.7:1, 92-octane fuel is recommended. The camshaft carries .525/.525-inch lift, and a duration of 226/236 degress at .050-inch. A Holley dual-plane intake, and Ultra 850 cfm double pumper reside under the chrome air cleaner that tops it off. The Pace Performance LS3 crate engine carries a Chevrolet Performance two year/50,000 mile warranty.

A quick call to Brian at Late Model Engines revealed their 416 LS3 crate engine. This baby comes with a long list of trick pieces to make this LS3 really haul the mail. The GM LS3 block is filled with a Callies Compstar crankshaft w/LME blueprinting process, ARP main studs, Compstar H-beam rods with gas ported Wiseco forged pistons and Clevite H-Series bearings. ARP head studs hold down the CNC-ported GM LS3 heads that flow 365 cfm through the intake, and 274 cfm out the exhaust. Finally, an LME-spec custom hydraulic-roller camshaft motivate the GM LS3 rocker arms with trunion modifications.

You have a choice of either a 9.5:1 or 10.0:1 compression ratio, as well as a list of wet sump oil pan styles to fit a variety of chassis. Brian let us know that with an Edelbrock single-plane LS3 carbureted intake and a 4150 series Holley carburetor, when fired by an MSD ignition, 700-plus horsepower is attainable while still being very streetable. If you need to go big or go home with a LS engine, Brian and the crew at Late Model Engines can make that happen for you.

It’ll cost you: $14,749.00

It’ll deliver: No numbers available, as this engine is delivered as a long block

Edelbrock starts with an LS3 aluminum block, and fills it with a forged 4340 crankshaft, forged H-beam rods, and forged aluminum pistons, building a 9.5:1 compression ratio. The camshaft sports a .629/.656-inch lift, and 215/247 degrees of exhaust duration. The GM cylinder heads are topped off with black powdercoated valve covers for a very clean look. Edelbrock says that a good intake manifold and carburetor choice would be an Edelbrock Victor Jr. manifold, and an Edelbrock 800 cfm carburetor. These would complete this LS3 in very fine fashion.

The Edelbrock 416 LS3 crate engine is also an excellent base for their E-Force supercharged engine that makes 720 horsepower, and is ideal for boosted applications as well. Edelbrock’s 416 LS3 crate engine carries a two-year/unlimited mile warranty, so you can drop this baby in and hit the road. With Edelbrock Performance’s long history of innovations, you can rest assured that new things to come will always be on the horzion.

It’ll Cost You: $13,777.99 to $14,799.77 (price varies by dealer)

It’ll Deliver: No numbers available, as this engine is delivered as a long block

Chris Storie at Scoggin Dickey Parts Center tells us their LS376 515 horsepower crate engine is a great choice for any LS swap. It’s the perfect high performance option for a classic project car. This small-cube powerhouse has a cast-aluminum block, a nodular iron, 3.622-inch stroke crankshaft, and a 10.7:1 compression ratio. The LS3 aluminum heads with L92-style ports have 2.165 and 1.590-inch valves, with high-flow, rectangular-port intake passages. The heart of the engine is a Chevrolet Performance hydraulic-roller camshaft with .525/.525-inch lift and 226/236-degrees of duration at .050-inch lift. Chris says he recommends using a Holley 770 cfm Street Avenger carburetor to finish off this crate engine. This combination will get you to the grocery store and back before you know it.

It’ll Cost You: $7,740.56

It’ll Deliver: 533 horsepower and 477 lb.ft. of torque

The LS-series engine swap, has taken the country by storm, as LS engines are found under the hoods of everything. Street rods, musclecars, and classic trucks have all benefited from an LS swap. LS engines are popping up in autocross and drag racing series’ across the country, because the lightweight, high horsepower potential is unbelieveable. Holley Performance Products even sponsors and promotes an entire weekend to the LS series engine with their Holley LS Fest.

While the traditional small-block Chevrolet engine has always been the standard of big performance in a small package, the LS-series engine, has proven that it’s here to stay. The folks at Chevrolet aren’t resting on their laurels, as they’re developing many innovating things for the LS engine inside the new GM Performance and Racing Center. This freshly completed 111,420 square-foot facility in Pontiac, Michigan, is where the sky is the limit for developing the latest in high-performance engines.

About the author

Steve Lewis

Steve has always been interested in all things mechanical since he was old enough to crawl. While growing up, he ravaged an untold number of bikes, trikes, Big Wheels, lawnmowers, and anything else with wheels. By the time he was 12 years old, Steve had already rebuilt his first engine and was working on rebuilding his first car – a 1963-1/2 Ford Galaxie 500 XL.
He moved into drag racing at 14, then street racing, and on to track racing at 16. At 28 he got his first taste of dirt track racing, and simultaneously did that and drag racing on and off for several years. Steve last drag raced in 2006, and currently is building a car to return to drag racing – a big- block 1976 Chevrolet Laguna S3. In between work and racing, he enjoys going to car shows and races.